It's an interesting question, and one asked by none other than Sandro Vanni the photographer who tends to have exclusive access to the Valley of the Kings. Sandro writes on Flickr:
The excavations uncovered 7 wooden coffins in the tomb, of which three had been painted with faces. They have been dated to just prior to King Tutankhamun's reign, and their fragile condition means that restoration has to be done carefully to ensure the sarcophagi don't disintegrate. Covered in thick, black resin, the coffins contained materials used in mummification as well as the remains of human flesh. Perhaps most telling is that on clearing out the coffins, the team found an imprint on the base, suggesting a mummy had been stored in there. It's not completely out of the question that somebody stole the mummy of KV63!This is a must visit link as it accompanies the best photo of the contents of KV63 I have ever seen which I guess shows the contents pretty much undisturbed in the tomb so that you can see how they related to each other in where they were found. For copyright reasons, I can't show it here so you have to visit Flickr.
It's one of a set of 10 fabulous photos of KV63. (Although the link there promises has has more photos on the Heritage Key page about KV63, he doesn't and the Heritage key page only has small versions of the photos. They are much better viewed on Flickr. The page itself isn't a bad page about KV63, but nor is it particularly great. If you've kept up to date on Otto Schaden's page, there's nothing that will interest too much.)